The present invention relates generally to a backup system for a volume or files in a Wide Area File System (WAFS). More particularly, the present invention relates to a backup system for a volume or files in a WAFS system when a cache is provided in a WAFS client of the WAFS system.
In today's environment the challenge of managing, for example, distributed enterprise efforts across multiple remote locations exists. While gigabytes of data can easily be shared on a local area network (LAN) using standard file server technology, these benefits do not extend to remote offices connected over a wide area network (WAN). When it comes to file sharing over WANs, standard file server protocols provide unacceptably slow response times when opening and writing files.
Various solutions have been proposed to solve the WAN file sharing problem including replicating file copies or implementing distributed file systems. Neither of these approaches provides a complete solution. Content delivery networks attempted to mitigate this problem by caching copies of files at each remote office. However, content delivery networks only provide a read-only copy of data at the remote offices.
WAFS systems combine distributed file systems with caching to allow real-time, read-write access to shared file storage from any location, while also providing interoperability with standard file sharing protocols such as the Network File System (NFS) and the Common Internet File System (CIFS) protocols. A WAFS system makes it possible to access a remote data center as though it were local. Such a system provides various benefits including enabling businesses, academic institutions, and government agencies having numerous branch offices to centrally manage data backups in real time.
In order to hide latency of file access from a client a cache server which is a WAFS client is used. Such a cache server is embodied in the iShared™ Server product marketed by TacitNetworks. Important properties of such a server are to maintain data coherency and consistency across the entire network. Although the TacitNetworks product provides a backup solution as described at Internet address: www.tacitnetworks.com/M03—01—03-Business-Continuity-Backup.php, there is no disclosure of how to backup data for a files of a WAFS server.
Prior cache based file systems in a WAN are disclosed, for example, by U.S. Patent Application Publication No. 2003/0163568 entitled “Storage System Management Data Through a Wide Area Network”, by Y. Kano, et al. In this application there is described a system and method of how to access a file from a client on LAN via WAN. However, this Patent Application Publication does not disclose how to make a complete procedure for making a backup from a centralized server on a remote data center.